Photodissociation Dynamics of highly excited molecules

Electrons image

When investigating the dynamics of highly excited molecules, our goal is to understand what happens to a molecule excited to energies close to its ionization limit. That energy region is usually dominated by Rydberg, valence (e.g. ion pair) and ionic states, whose interaction (or lack of interaction) we want to understand better. In collaboration with the group of Prof. A. Kvaran (University of Iceland, Iceland) we have looked into the dynamics of HBr, CH3Br and CH3I.

Related publications:
D. Zaouris, A. Kartakoullis, P. Glodic, P. C. Samartzis, H.R. Hrodmarsson, A.  Kvaran, Rydberg and valence state excitation dynamics: a velocity map imaging study involving the E-V state interaction in HBr, Phys Chem.Chem.Phys.17, 10468 (2015)

P. Glodic, D. Zaouris, P.C. Samartzis, A. Haflidason, A. Kvaran,Effect of a triplet to singlet state interaction on photofragmentation dynamics: highly excited states of HBr probed by VMI and REMPI as a case study, Phys Chem.Chem.Phys.18, 26291 (2016)

H. R. Hrodmarsson, A. K. Kartakoullis, D. Zaouris, P. Glodic, H. Wang, P. C. Samartzis, A. Kvaran, Excitation dynamics involving homogeneous multistate interactions: one and two color VMI and REMPI of HBr, Phys Chem.Chem.Phys.19, 11354 (2017)

A. Haflidason, P. Glodic, G. Koumarianou, P. C. Samartzis and A. Kvaran, Multiphoton Rydberg and valence dynamics of CH3Br probed by mass spectrometry and slice imaging, Phys .Chem. Chem. Phys. 20, 17423 (2018)

A. Haflidason, P. Glodic, G. Koumarianou, P. C. Samartzis and A. Kvaran, Two-color studies of CH3Br excitation dynamics with MPI and slice imaging, Phys .Chem. Chem. Phys. 21, 10391 (2019)

K. Matthıasson, G. Koumarianou, M. X. Jiang, P. Glodic, P. C. Samartzis, A. Kvaran, Formation of highly excited iodine atoms from multiphoton excitation of CH3I, Phys .Chem. Chem. Phys. 22, 4984 (2020)


Photoelectron Circular Dichroism of chiral molecules
 

When chiral molecules are ionized with circularly polarized light, the electron distribution produced has a forward-backward asymmetry in the laser propagation direction, dependent on the enantiomer used and on photon helicity, an effect known as Photoelectron Circular Dichroism (PECD). We investigate if and how PECD changes with the excitation energy and scheme used to ionized the chiral molecule.   
In collaboration with the teams of Tim Schaefer (Gottingen, Germany) and Thomas Baumert (Kassel, Germany), we demonstrated the first tunable nanosecond PECD data using a dye ns laser for multiphoton ionization of fenchone enantiomers at different wavelengths in order to discover whether PECD depends on the vibrational level of the intermediate state. Our data suggest that is doesn’t, but further investigation in different regions and molecules is needed to confirm.

Related publication:
A. Kastner, G. Koumarianou, P. Glodic, P. C. Samartzis, N. Ladda, S. T. Ranecky, T. Ring, S. Vasudevan, C. Witte, H. Braun, H. G. Lee, A. Senftleben, R. Berger, G. B. Park, T. Schäfer,  T. Baumert, High-resolution resonance-enhanced multiphoton photoelectron circular dichroism, Phys .Chem. Chem. Phys. 22, 7404 (2020)

Analysis using photons

Spectroscopic detection of (fossil) fuels adulteration:We combine statistical analysis methods and spectroscopic data (UV to NIR absorption, fluorescence, FT-IR) of pure fossil fuels (gasolines, diesels) and adulterants (solvents, lubricants, lubricants waste) and their mixtures aiming to develop a system that will detect fuel adulteration spectroscopically in a reliable, cheap and user-friendly way.  This work is part of a general direction aiming to improve how we detect molecules of choice in a chemical mixture.


Time-Resolved Electron Diffraction probes for Chemistry and Materials Science

In this direction we aim to develop time-resolved electron diffraction probes for applications in chemistry and materials science. Ultrafast Electron Diffraction and similar techniques exist for more than 20 years, however they are not widely used in chemistry and materials. We want to use the lessons of those years and adapt UED for use in chemistry (e.g. dark reactions, structural dynamics) and materials science (e.g. excitation energy redistribution, lattice dynamics).